It's time for the NHS to wake up to climate change. Global warming is the biggest threat to our future health. This isn't a message that has yet seeped into the public consciousness. It isn't a message that most doctors and nurses think is relevant to health. But it's time that health professionals stood on the front lines of political debate to explain why climate change is the most serious danger to our wellbeing, even to our survival.

The threat of climate change is with us now. A two-year commission between The Lancet and University College London (pdf), published today, sets out the scale of the threat to human health posed by climate change. "Even the most conservative estimates are profoundly disturbing and demand action", the UCL team of health, climate change, and environmental scientists, together with lawyers, political scientists, and economists, conclude in Managing the Health Effects of Climate Change. This is an issue that should not only matter to us now. We should be concerned because of what is likely to happen to the health of our children and grandchildren in the future.

We know that as temperatures rise, extreme climatic events will cause heatwaves, floods, and unusually strong storms. People in Britain will die. The incidence of infections, cataracts, and skin cancers will rise. More people will be admitted to hospital.

But the greatest impacts will be on the poorest peoples in the world today. Africa will endure yet another crisis to add to its existing predicaments of poverty, disease, and economic collapse. The warming of the planet will trigger new epidemics of infectious diseases. Food yields will fall and millions of people will suffer starvation. 250 million more people in Africa will face water poverty by 2020. Poor housing and slums will be especially vulnerable to extreme climatic events. The millions of people who migrate away from places of climatic stress will create new tensions, precipitating violence and war.

Climate change seems too big, too complex, too unpredictable, too global, and too distant. It's tempting to give up when confronted by this prospect of human catastrophe. There is much that we don't know about what climate change might do. We are frightened by this terrifying uncertainty. We need new technologies to pull us back from the edge of disaster. We need new ways to solve the stubborn problem of global poverty. We need ways to get the public and politicians to take climate change more seriously. Climate change should be a major priority for our political parties in the 2010 general election.

Despite reasons for despair, our commission remains optimistic. We can do something, and the health community, in particular, can do a great deal to lead a movement to protect billions of people from the health effects of climate change. We did it once before. It took 20 years – from the 1940s to the 1960s – to assemble the science to prove that smoking damaged human health. It took another 40 years to translate that science into a ban on smoking in public places. We have reached the point where we can be confident of the cataclysmic effects of climate change on health. But we don't have the luxury of 40 years to change public policy. Every decade of delay will push up the peak temperature of the earth to increasingly unsustainable levels.

The NHS is Britain's largest employer. If those who work in it now back a radical agenda to change our lifestyle to low-carbon living we will make a big and valuable contribution to saving our fragile human species. Climate change is the biggest global health threat of the 21st century. But health is possibly the best means to mobilise political action to face down that threat. Because without health there is no life for us or our children.